This invention is related to tools and, more particularly, to tools for performing operations requiring an application of a severing or squeezing force, such as cutting or crimping metal rods, bolts and cables.
Many tools in this field are limited to one specific function. Thus, a user must acquire and maintain a large amount of hardware in the course of doing business. In addition, most tools designed for a particular task do not provide any versatility, even for that particular task.
Many tools have been designed to provide additional versatility, but many of those tools have sacrificed some of the qualities inherent in single-purpose tools. For instance, in the past, if a user desired to cut metal rods or bolts and cut cables, they were required to purchase two separate tools (i.e., one for cutting metal rods or bolts and another for cutting cables). Two tools were required because well-known bolt cutters with straight edge jaws perform very poorly on cables.
One tool designed to cut both rods and cables is disclosed in U.S. Pat. No. 6,185,825 to Olson. As well as making an attempt to solve the problem described above, Olson attempted to bring the cutting action very close to a common pivot point of two cutting blades, while substantially reducing the size of the blades (see FIGS. 1A and 1B). However, the tool requires highly specialized hardware for sharpening the blades and it is critical to maintain the sharpness of the blades for cutting cable. Blades have a tendency to wear out with use. If the cutting edges wear out or dull even slightly and are used to cut cable, they tend to shear through a portion of the cable's thickness and then “chew” on the cable between the blades. Plus, after only a few sharpening cycles, the entire tool must be discarded because there is no provision for replaceable blades. Furthermore, the tool uses blades configured to shear that are enclosed inside one another, which requires the tool to have a width exceeding that of squeezing or crushing type cutters and limits to the tool's usefulness.
U.S. Pat. No. 5,862,597 to Juros (see FIGS. 2A–2C), discloses a tool that makes it possible to bring the cutting action as close to a point of applied force as physically allowable, but doing so comes at a cost. Considering structural properties of the materials involved, the width of the tool must exceed that of most conventional cutters, thus restricting its use in narrow openings, such as between pipe flange faces. The tool employs fully circular eccentrically pivoted bosses to increase the mechanical advantage, and as a result, the tool's handles must be opened to a notably greater angle. For all practical purposes the increased angle nullifies the benefit of the handles being shorter, and makes them unsafe and uncomfortable to use. Additionally, the tool does not provide for inexpensive and easily replaceable blades.
Devices described in WO Publication No. 9505271 to Cooper (see FIG. 3A), U.S. Pat. No. 6,226,874 to Jansson (see FIG. 3B) and conventional, widely sold bolt cutters (see FIG. 3C), along with many others featuring a similar configuration, present another well-known approach to the subject of the cutter's longevity. In particular, they provide various means for adjusting the blades after their sharpening. Nevertheless, eventually one still has to replace blades that cost nearly as much as an entire new tool.
The issue of replaceable blades was addressed by EP0011545 to Muller (see FIG. 4A) and U.S. Pat. No. 5,898,998 to Deville (see FIG. 4B), but the solution suggested therein, while being suitable for use in many tool designs, is not entirely satisfactory. First, the design weakens the blade support. The design also does not facilitate a uniform transfer and distribution of tension within the metal structures of the blade and blade support, which accelerates fatigue of the structures.
All four of latter inventions suffer from an obvious departure from keeping the cutting action near the point of applied force, so these tools, once again, demand an application of greater force to their handles.
An illustrative example of loss of versatility in favor of improving a narrow aspect can be seen in German Patent No. 3402544 to Hoffmann (see FIG. 4C). It completely eliminates slippage of a material that is being cut away from the point of applied force. In exchange, this improvement renders the cutter practically incapable of cutting anything thinner than the distance between the jaws when they are opened to about two-thirds of their capacity.
Tools that feature power sources are, for purposes of the present discussion, represented by disclosures of U.S. Pat. No. 4,587,732 to Lind et al. (see FIG. 5A), U.S. Pat. No. 4,760,644 to Yirmiyahu et al. (see FIG. 5B) and JP 02002078988 to Oide (see FIG. 5C). These tools can readily utilize a variety of attachments for different operations. But such attachments come at relatively high cost, and, except for JP 02002078988, it is doubtful that they are easily demountable. Also, these inventions solve practically none of the other shortcomings discussed above.
Operations falling into a category of “cutting” had been discussed thus far. This was done in an attempt to make it clear that a challenge of finding an optimal combination of most efficient means for accomplishing even slightly varying tasks remains unanswered by the conventional art.
With the exception of U.S. Pat. No. 6,185,825 to Olson (see FIGS. 1A–1B) and U.S. Pat. No. 5,862,597 to Juros (see FIGS. 2A–2C), whose tools utilize one stage lever action, other previously discussed manual cutters use handles as levers of a first stage, and blades as levers of a second stage.
The present invention introduces not only such combination, but also a far greater degree of versatility while sacrificing very few or none of the other benefits that elements of the combination provide individually.